1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling. 4 * Part of the Linux-NTFS project. 5 * 6 * Copyright (c) 2005 Anton Altaparmakov 7 */ 8 9 #ifndef _LINUX_NTFS_USNJRNL_H 10 #define _LINUX_NTFS_USNJRNL_H 11 12 #ifdef NTFS_RW 13 14 #include "types.h" 15 #include "endian.h" 16 #include "layout.h" 17 #include "volume.h" 18 19 /* 20 * Transaction log ($UsnJrnl) organization: 21 * 22 * The transaction log records whenever a file is modified in any way. So for 23 * example it will record that file "blah" was written to at a particular time 24 * but not what was written. If will record that a file was deleted or 25 * created, that a file was truncated, etc. See below for all the reason 26 * codes used. 27 * 28 * The transaction log is in the $Extend directory which is in the root 29 * directory of each volume. If it is not present it means transaction 30 * logging is disabled. If it is present it means transaction logging is 31 * either enabled or in the process of being disabled in which case we can 32 * ignore it as it will go away as soon as Windows gets its hands on it. 33 * 34 * To determine whether the transaction logging is enabled or in the process 35 * of being disabled, need to check the volume flags in the 36 * $VOLUME_INFORMATION attribute in the $Volume system file (which is present 37 * in the root directory and has a fixed mft record number, see layout.h). 38 * If the flag VOLUME_DELETE_USN_UNDERWAY is set it means the transaction log 39 * is in the process of being disabled and if this flag is clear it means the 40 * transaction log is enabled. 41 * 42 * The transaction log consists of two parts; the $DATA/$Max attribute as well 43 * as the $DATA/$J attribute. $Max is a header describing the transaction 44 * log whilst $J is the transaction log data itself as a sequence of variable 45 * sized USN_RECORDs (see below for all the structures). 46 * 47 * We do not care about transaction logging at this point in time but we still 48 * need to let windows know that the transaction log is out of date. To do 49 * this we need to stamp the transaction log. This involves setting the 50 * lowest_valid_usn field in the $DATA/$Max attribute to the usn to be used 51 * for the next added USN_RECORD to the $DATA/$J attribute as well as 52 * generating a new journal_id in $DATA/$Max. 53 * 54 * The journal_id is as of the current version (2.0) of the transaction log 55 * simply the 64-bit timestamp of when the journal was either created or last 56 * stamped. 57 * 58 * To determine the next usn there are two ways. The first is to parse 59 * $DATA/$J and to find the last USN_RECORD in it and to add its record_length 60 * to its usn (which is the byte offset in the $DATA/$J attribute). The 61 * second is simply to take the data size of the attribute. Since the usns 62 * are simply byte offsets into $DATA/$J, this is exactly the next usn. For 63 * obvious reasons we use the second method as it is much simpler and faster. 64 * 65 * As an aside, note that to actually disable the transaction log, one would 66 * need to set the VOLUME_DELETE_USN_UNDERWAY flag (see above), then go 67 * through all the mft records on the volume and set the usn field in their 68 * $STANDARD_INFORMATION attribute to zero. Once that is done, one would need 69 * to delete the transaction log file, i.e. \$Extent\$UsnJrnl, and finally, 70 * one would need to clear the VOLUME_DELETE_USN_UNDERWAY flag. 71 * 72 * Note that if a volume is unmounted whilst the transaction log is being 73 * disabled, the process will continue the next time the volume is mounted. 74 * This is why we can safely mount read-write when we see a transaction log 75 * in the process of being deleted. 76 */ 77 78 /* Some $UsnJrnl related constants. */ 79 #define UsnJrnlMajorVer 2 80 #define UsnJrnlMinorVer 0 81 82 /* 83 * $DATA/$Max attribute. This is (always?) resident and has a fixed size of 84 * 32 bytes. It contains the header describing the transaction log. 85 */ 86 typedef struct { 87 /*Ofs*/ 88 /* 0*/sle64 maximum_size; /* The maximum on-disk size of the $DATA/$J 89 attribute. */ 90 /* 8*/sle64 allocation_delta; /* Number of bytes by which to increase the 91 size of the $DATA/$J attribute. */ 92 /*0x10*/sle64 journal_id; /* Current id of the transaction log. */ 93 /*0x18*/leUSN lowest_valid_usn; /* Lowest valid usn in $DATA/$J for the 94 current journal_id. */ 95 /* sizeof() = 32 (0x20) bytes */ 96 } __attribute__ ((__packed__)) USN_HEADER; 97 98 /* 99 * Reason flags (32-bit). Cumulative flags describing the change(s) to the 100 * file since it was last opened. I think the names speak for themselves but 101 * if you disagree check out the descriptions in the Linux NTFS project NTFS 102 * documentation: http://www.linux-ntfs.org/ 103 */ 104 enum { 105 USN_REASON_DATA_OVERWRITE = cpu_to_le32(0x00000001), 106 USN_REASON_DATA_EXTEND = cpu_to_le32(0x00000002), 107 USN_REASON_DATA_TRUNCATION = cpu_to_le32(0x00000004), 108 USN_REASON_NAMED_DATA_OVERWRITE = cpu_to_le32(0x00000010), 109 USN_REASON_NAMED_DATA_EXTEND = cpu_to_le32(0x00000020), 110 USN_REASON_NAMED_DATA_TRUNCATION= cpu_to_le32(0x00000040), 111 USN_REASON_FILE_CREATE = cpu_to_le32(0x00000100), 112 USN_REASON_FILE_DELETE = cpu_to_le32(0x00000200), 113 USN_REASON_EA_CHANGE = cpu_to_le32(0x00000400), 114 USN_REASON_SECURITY_CHANGE = cpu_to_le32(0x00000800), 115 USN_REASON_RENAME_OLD_NAME = cpu_to_le32(0x00001000), 116 USN_REASON_RENAME_NEW_NAME = cpu_to_le32(0x00002000), 117 USN_REASON_INDEXABLE_CHANGE = cpu_to_le32(0x00004000), 118 USN_REASON_BASIC_INFO_CHANGE = cpu_to_le32(0x00008000), 119 USN_REASON_HARD_LINK_CHANGE = cpu_to_le32(0x00010000), 120 USN_REASON_COMPRESSION_CHANGE = cpu_to_le32(0x00020000), 121 USN_REASON_ENCRYPTION_CHANGE = cpu_to_le32(0x00040000), 122 USN_REASON_OBJECT_ID_CHANGE = cpu_to_le32(0x00080000), 123 USN_REASON_REPARSE_POINT_CHANGE = cpu_to_le32(0x00100000), 124 USN_REASON_STREAM_CHANGE = cpu_to_le32(0x00200000), 125 USN_REASON_CLOSE = cpu_to_le32(0x80000000), 126 }; 127 128 typedef le32 USN_REASON_FLAGS; 129 130 /* 131 * Source info flags (32-bit). Information about the source of the change(s) 132 * to the file. For detailed descriptions of what these mean, see the Linux 133 * NTFS project NTFS documentation: 134 * http://www.linux-ntfs.org/ 135 */ 136 enum { 137 USN_SOURCE_DATA_MANAGEMENT = cpu_to_le32(0x00000001), 138 USN_SOURCE_AUXILIARY_DATA = cpu_to_le32(0x00000002), 139 USN_SOURCE_REPLICATION_MANAGEMENT = cpu_to_le32(0x00000004), 140 }; 141 142 typedef le32 USN_SOURCE_INFO_FLAGS; 143 144 /* 145 * $DATA/$J attribute. This is always non-resident, is marked as sparse, and 146 * is of variabled size. It consists of a sequence of variable size 147 * USN_RECORDS. The minimum allocated_size is allocation_delta as 148 * specified in $DATA/$Max. When the maximum_size specified in $DATA/$Max is 149 * exceeded by more than allocation_delta bytes, allocation_delta bytes are 150 * allocated and appended to the $DATA/$J attribute and an equal number of 151 * bytes at the beginning of the attribute are freed and made sparse. Note the 152 * making sparse only happens at volume checkpoints and hence the actual 153 * $DATA/$J size can exceed maximum_size + allocation_delta temporarily. 154 */ 155 typedef struct { 156 /*Ofs*/ 157 /* 0*/le32 length; /* Byte size of this record (8-byte 158 aligned). */ 159 /* 4*/le16 major_ver; /* Major version of the transaction log used 160 for this record. */ 161 /* 6*/le16 minor_ver; /* Minor version of the transaction log used 162 for this record. */ 163 /* 8*/leMFT_REF mft_reference;/* The mft reference of the file (or 164 directory) described by this record. */ 165 /*0x10*/leMFT_REF parent_directory;/* The mft reference of the parent 166 directory of the file described by this 167 record. */ 168 /*0x18*/leUSN usn; /* The usn of this record. Equals the offset 169 within the $DATA/$J attribute. */ 170 /*0x20*/sle64 time; /* Time when this record was created. */ 171 /*0x28*/USN_REASON_FLAGS reason;/* Reason flags (see above). */ 172 /*0x2c*/USN_SOURCE_INFO_FLAGS source_info;/* Source info flags (see above). */ 173 /*0x30*/le32 security_id; /* File security_id copied from 174 $STANDARD_INFORMATION. */ 175 /*0x34*/FILE_ATTR_FLAGS file_attributes; /* File attributes copied from 176 $STANDARD_INFORMATION or $FILE_NAME (not 177 sure which). */ 178 /*0x38*/le16 file_name_size; /* Size of the file name in bytes. */ 179 /*0x3a*/le16 file_name_offset; /* Offset to the file name in bytes from the 180 start of this record. */ 181 /*0x3c*/ntfschar file_name[0]; /* Use when creating only. When reading use 182 file_name_offset to determine the location 183 of the name. */ 184 /* sizeof() = 60 (0x3c) bytes */ 185 } __attribute__ ((__packed__)) USN_RECORD; 186 187 extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol); 188 189 #endif /* NTFS_RW */ 190 191 #endif /* _LINUX_NTFS_USNJRNL_H */ 192